JP2682849B2 - Heat exchanger and manufacturing method thereof - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat exchanger mainly composed of high thermal conductive ceramics suitable for a water heater, a radiator and the like, and a method for manufacturing the same.

(Prior Art) As a heat exchanger used in a water heater or the like, there is a heat exchanger in which a plurality of parallel heat exchange medium distribution pipes and a large number of fins are combined and configured. This type of heat exchanger that has been conventionally used is mainly made of all metal, which is generally configured by combining copper fins and pipes. Recently, JP-A-62-70035 and JP-A-62-70042 have also proposed a structure made of only a ceramic material having excellent heat resistance and corrosion resistance. As shown in FIG. 4, this heat exchanger made of ceramics is prepared by screwing pipes p ... Into a honeycomb body (assembly of fins) h having pipe insertion holes f ... and h are fixed by a glass-like bonding material, or glass paste is applied in advance to the honeycomb structure h ₁ ... which is divided as shown in FIG. 5, and the pipes p are sandwiched to obtain both as a fixed unit. To be

(Problems to be Solved by the Invention) Of the above, the all-metal heat exchanger is difficult to use at high temperature because of poor heat resistance, and therefore not only the heat exchange efficiency is poor, but also a corrosion-resistant substance. When exhaust gas containing exhaust gas, exhaust liquid, etc. come into contact with each other, they easily corrode, which shortens the service life.

On the other hand, a ceramic heat exchanger has a high temperature characteristic and excellent corrosion resistance, but has a fatal defect of poor thermal conductivity. Is not good, and because the thermal conductivity is poor,
When the size was increased like the No. 10 type, or when the burner was brought closer, an extreme temperature distribution was generated inside and there was the drawback that it would crack due to thermal stress, and in addition there was a cost problem. Also, when a pipe is inserted into a ceramic honeycomb body, it is difficult to maintain good thermal conductivity for all joints between the pipe and each lattice (fin), and even if the honeycomb body is a divided body, Since it is a honeycomb body, the pressure loss of the flowing gas is large and the heat exchange efficiency is unavoidable.

(Object of the invention) The present invention has been made in view of the above, and a novel heat exchanger having a long life and excellent heat exchange efficiency even when exposed to high temperature and corrosion conditions, and an effective manufacturing method thereof. Is intended to be provided.

(Means for Solving the Problems) The configuration of the present invention for achieving the above object will be described with reference to the attached embodiment drawings. FIG. 1 is an overall perspective view showing an example of the heat exchanger of the present invention, FIG. 2 is a perspective view of pipes and fins constituting the heat exchanger, and FIG. 3 is a jig for manufacturing the heat exchanger. FIG.

That is, the heat exchanger which is the specific invention of the present invention includes a plurality of vertically parallel heat exchange medium distribution pipes 1, ..., Which are mounted in parallel to each other so as to be orthogonal to the pipes 1 ... Made up of a large number of plate-shaped fins 2 ... 3 ..., and the pipe 1 ... And the fins 2 ... 3 ... are made of copper at the low temperature side, and the high temperature side is made of high heat conductive material such as silicon carbide or aluminum nitride. And the fins 2 ... 3 are joined and integrated by an active metal layer.

In the method for manufacturing a heat exchanger according to the second aspect of the present invention, a plurality of heat exchange medium distribution pipes 1 ... And a large number of plate-shaped fins 2 ... 3 ... Are made of high thermal conductive ceramics such as silicon carbide or aluminum nitride. , Other pipe 1 ... and fins 2 ... 3
Are formed of copper, and the fins 2 are erected in a large number of parallel grooves that are recessed at equal intervals on the inner bottom surface of the assembly jig and the striking surfaces on both sides of the assembly jig whose upper surface is open. A plurality of vertically parallel pipes 1 are formed by sequentially stacking the fins 2 ... 3 and the pipes 1 ... by arranging the pipes 1 ... To many plate-shaped fins 2
, 3 are arranged in parallel with each other so as to maintain the pipes 1 in an orthogonal state, and a part of the pipes 1 and the fins 2 ... Made of conductive ceramics, other pipe 1
... and fins 2 ... 3 ... are assembled into a structure made of copper,
Next, this structure is placed under a reduced pressure atmosphere of 10 ⁻³ to 10 ⁻⁵ torr at 80 ° C.
The gist is that the pipes 1 ... And the fins 2 ..., 3 ... Are integrally joined by heating at 0 to 1000.degree. C. and thermal fusion of the active metal layer.

As the high thermal conductive ceramics of the present invention, silicon carbide, aluminum nitride, or the like is desirably adopted as described above. The thermal conductivity of silicon carbide is 63 watts / m · K or more, and the thermal conductivity of aluminum nitride is 120 watt / m
-It is K or more.

The active metal layer in which the pipes 1 ... And the fins 2 ... 3 are integrally bonded is formed by applying or pasting a paste or foil of titanium, copper, silver or the like on the circumference of each pipe 1 in advance. Is formed. This active metal layer is melted by heating in the above-mentioned reduced pressure atmosphere, and the pipes 1 ...
3 ... are integrally joined, but when the vacuum degree exceeds 10 ³ torr, the active metal is easily oxidized, while when the vacuum degree is less than 10 ⁻⁵ torr, the molten active metal is easily evaporated. When the heating temperature is lower than 800 ° C, the active metal is not sufficiently melted, and when the heating temperature is higher than 1000 ° C, the active metal is easily oxidized and evaporated.

(Operation) The heat exchanger having the above configuration is incorporated in the hot water supply device, the radiator, or the like. Then, the heat exchange medium circulates in the pipes 1 ..., The other heat exchange medium circulates in contact with the fins 2, ..., 3, so that heat is exchanged between the two media. At this time, since the pipes 1 ... And the fins 2 ... 3 are made of a highly heat-conductive material and are arranged in parallel with each other in the form of fins 2 ... 3 ..., the heat exchange medium has a small pressure loss and is extremely small. Heat is exchanged efficiently. Further, the portion made of the above-mentioned ceramics can sufficiently withstand even when exposed to high temperature. Furthermore, since the ceramics have high thermal conductivity, even if the heat exchanger is upsized or the burner is brought close to the ceramics, temperature distribution is unlikely to occur inside, and there is no fear of cracking due to thermal stress. In particular, since the upper half of the heat exchanger body is made of copper and the lower half is made of the above-mentioned high thermal conductive ceramics, it can be used at high temperatures and the burner capacity can be increased. Can be made compact. Further, since the upper half of the relatively low temperature is made of copper, the temperature distribution can be narrowed due to its excellent thermal conductivity, and the thermal stress becomes large.

A method for manufacturing the heat exchanger will be specifically described. First, the above-mentioned active metal layer is adhered and formed on the peripheral body of the pipes 1 ...
, 3 are arranged in the carbon assembling jig 4 as shown in the embodiment described later so as to have the above-mentioned positional relationship, and this is heat-treated for about 30 minutes in the furnace maintained under the above-mentioned atmospheric conditions. When the jig 4 is removed after the heat treatment, as shown in FIG. 1, a heat exchanger in which the pipes 1 ... And the fins 2 ...

Since the fusion layer of the active metal is interposed at the joint between the pipe 1 ... And the fins 2 ... 3 in the heat exchanger thus obtained, the joint strength is large and The thermal conductivity is good. Moreover, this heat exchanger is constructed so that the pipes 1 ...
It can be easily manufactured because it is necessary only to sequentially stack 3 ...

(Example) Next, an example is described. FIGS. 2 (A), (B) and (C) show the shapes of the pipes and fins constituting the heat exchanger of the present invention. The pipe 1 has an outer diameter of about 16 mm, and is kneaded by adding a proper amount of a sintering aid and a binder to a ceramic raw material such as silicon carbide or aluminum nitride, and kneading the kneaded product from a predetermined mold into a cylinder. It is obtained by extruding into a shape and firing the molded body in an atmosphere suitable for each ceramic body, or a commercially available copper tube cut into a predetermined size. The fins 2 and 3 are plate-like bodies having substantially semi-circular cutouts 21 and 31 that can hold the outer periphery of the pipe 1, and two types are illustrated as shown in FIG. 2 (b) and (c). There is. These fins 2 and 3 are obtained by press-molding a ceramic raw material similar to the above and subjecting it to post-firing, or by punching a commercially available copper plate.

An active metal layer is formed on the peripheral body of the pipe 1 as described above, and is placed in the carbon assembly jig 4 shown in FIG. 3 together with the fins 2 and 3 and subjected to vacuum heat treatment. That is, the assembling jig 4 is framed by a carbon frame material in a box shape having an open upper surface, and a large number of parallel grooves for vertically arranging fins on the inner bottom surface and both inner surfaces thereof are provided. 41 ... are recessed at equal intervals. The fins 2 shown in FIG. 2 (b) are successively fitted and set up in the grooves 41 so that the cutouts 21 face upward, and the pipe 1 is laterally placed in the recesses formed by a series of cutouts 21. The intermediate fin 3 shown in FIG. 2 (c) is inserted into the groove 41 of the side portion, and the peripheral portion of the pipe 1 which is already crossed by the cutout portion 31 on the lower side is held. Let Next, another pipe 1 is placed horizontally in the recess formed by the notch 31 formed on the upper side of the fin 3, and another fin 3 is placed upside down in the same manner and the other pipe 1 is placed on top of it. After mounting, the fin 2 similar to the bottom is turned upside down and the groove 41
… Insert and hold in between. In this state, the pipes 1 ... Are held parallel to each other in the vertical direction, and the fins 2 ... 3 are held in the pipes 1 ... When the pipe 1 bends in the middle, it is possible to interpose a separately prepared spacer (not shown) in the middle.

When the structure thus prepared is heat-treated as it is under the above-mentioned conditions, the active metal adhered to the peripheral body of the pipe 1 ... Is melted, and the pipe 1 ... And the fins 2 ... When they are attached and hardened, they are firmly joined and integrated. After that, when the assembling jig 4 is removed, a heat exchanger as shown in FIG. 1 is obtained.

The heat exchanger of FIG. 1 includes five pipes 1 ... Which are evenly arranged in parallel in the vertical direction and four types (substantially two types) of fins 2 ,.
It is fixed and integrated so that it is sandwiched from above and below. The heat exchanger has pipes 1 ... And fins 2 ... 3 ... made of copper on the low temperature side, and a lower part of the high temperature side is made of aluminum nitride ceramics. When the heat exchange efficiency was measured under the same specifications and under the same conditions, the former had a better heat exchange efficiency of about 10%, and the passage resistance of the heat exchange medium was smaller, so the rotation speed of the medium supply fan was significantly higher It was also confirmed that it would lower the equipment noise. It was also confirmed that the heat exchanger of the present invention has a small heat distribution and can be brought closer to the burner.

(Effects of the Invention) As described above, in the heat exchanger of the present invention, the fins of the pipe are made of high thermal conductive ceramics and copper, and the plate-shaped fins are mounted so as to be orthogonal to and parallel to the pipe. Therefore, the flow resistance of the heat exchange medium is small, the heat exchange medium can withstand high temperatures sufficiently, and the heat exchange efficiency is extremely large. Also, the heat distribution is small, especially the upper part on the low temperature side is made of copper,
Since the lower part on the high temperature side is composed of the above high thermal conductivity ceramics, the heat distribution is small even when exposed to high temperature, the burner capacity can be increased or the burner can be brought closer, contributing to the compactification of the heat exchanger. On the contrary, it becomes possible to cope with the increase in size.

On the other hand, in the manufacturing method of the present invention, an upper surface of the assembly jig is opened, and a plurality of parallel grooves are formed in the inner bottom surface and the inner surfaces of both sides at equal intervals for assembly. Since the pipes and the fins are sequentially stacked so as to maintain the positional relationship between the pipes, a plurality of upper and lower parallel pipes constituting the heat exchanger of the present invention and the pipes are orthogonal to the pipes and the pipes are held at intervals. It can be easily assembled into a structure consisting of a large number of plate-shaped fins arranged in parallel with each other, and the pipe and the fin are integrally joined by heat fusion of the active metal layer previously formed on the pipe. Therefore, both can be firmly integrated, and a highly accurate and high-performance heat exchanger can be provided.

As described above, the present invention promises to increase the suitability for the water heater and the radiator, and its value is extremely large.

[Brief description of the drawings]

FIG. 1 is an overall perspective view showing an example of the heat exchanger of the present invention, and FIG.
Fig. 3 is a perspective view of pipes and fins constituting the heat exchanger, Fig. 3 is a perspective view of a jig for manufacturing the heat exchanger, and Figs. 4 and 5 are perspective views of a conventional heat exchanger. It is a figure. (Explanation of symbols) 1 ... Pipe, 2 ... 3 Fin, 4 ... Assembly jig.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 62-70035 (JP, A) JP 53-113742 (JP, A) Actual opening 62-160172 (JP, U) Actual opening 63- 5339 (JP, U)

Claims (2)

(57) [Claims] 1. A low-temperature side comprising a plurality of heat-exchange-medium distribution pipes which are parallel to each other in the vertical direction, and a large number of plate-shaped fins which are mounted in parallel to each other in a state orthogonal to the pipes and hold the pipes at intervals. The upper pipe and fin are made of copper, the lower pipe and fin on the high temperature side are made of high thermal conductive ceramics such as silicon carbide or aluminum nitride, and the pipe and fin are joined and integrated by an active metal layer. Characteristic heat exchanger. 2. A plurality of heat exchange medium distribution pipes and a large number of plate-shaped fins are partially formed of high thermal conductive ceramics such as silicon carbide or aluminum nitride, and the other pipes and a large number of fins are formed of copper, respectively. After the fins are erected in a large number of parallel grooves recessed at equal intervals on the inner bottom surface and both inner surfaces of the open assembly jig, an active metal layer is formed on the peripheral body so as to be orthogonal to these fins. By sequentially stacking the fins and the pipes by arranging the above-mentioned pipes, a large number of plate-like fins are arranged in parallel in a plurality of vertically parallel pipes so as to hold the pipes in an orthogonal state. In addition, a structure in which some of the above pipes and fins are made of high thermal conductive ceramics such as silicon carbide or aluminum nitride, and other pipes and fins are made of copper Was assembled, then this structure 10
^A method for producing a heat exchanger in which a pipe and a fin are integrally joined by heat fusion of the active metal layer by heating at 800 to 1000 ° C. under a reduced pressure atmosphere of ⁻³ to 10 ⁻⁵ torr.